Coatings for transportation means, such as, for example, motor vehicles, airplanes and rail-mounted vehicles, may combine both functions of decoration and protection. In many circumstances, the coatings are developed to withstand extreme demands with respect to corrosion protection, scratch resistance, optics, coloring, chemical resistance, and resistance to other possible environmental effects.
Currently, coatings such as composite paints may comprise at least one multifunctional layer. For example, a composite paint such as an automotive topcoat may contain a basecoat (e.g., color coat) which is applied separately and before the application of a separate clearcoat. The functions of the top layer may include protecting coating pigments from the elements of weather, providing scratch and mar resistance, and providing gloss and the depth of field.
Typically, coatings may comprise additional constituents including pigment dispersions used to impart color. Conventional pigments utilized may include titanium dioxide (TiO2), graphite, and carbon black, for example. In producing known pigmented coating compositions, particularly in multi-layered (e.g., self-stratifying or self-layering) compositions, it is uncertain whether the pigment dispersion may segregate in a particular layer or be found throughout the coating. In certain applications, it may be desirable to produce a pigmented top or intermediate film layer within a composite paint. Thus, a need exists for methods to control the location of pigments within self-stratifying or self-layering coating compositions.